Detailed operational building data for six office rooms in Denmark: Occupancy, indoor environment, heating, ventilation, lighting and room control monitoring with sub-hourly temporal resolution

The operational building data presented in this paper has been collected from six office rooms located in an office building (research and educational purposes) located on the main campus of Aalborg University in Denmark. The dataset consists of measurements of occupancy, indoor environmental quality, room-level and system-level heating, ventilation and lighting operation at a 5 min resolution. The indoor environmental quality and building system data were collected from the building management system. The occupancy level in each monitored room is established from the computer vision-based analysis of wall-mounted camera footage of each office. The number of people present in the room is estimated using the YOLOv5s image recognition algorithm. The present dataset can be used for occupancy analysis, indoor environmental quality investigations, machine learning, and model predictive control.

Simulating human exposure to indoor airborne microplastics using a Breathing Thermal Manikin

Humans are potentially exposed to microplastics through food, drink, and air. The first two pathways have received quite some scientific attention, while little is known about the latter. We address the exposure of humans to indoor airborne microplastics using a Breathing Thermal Manikin. Three apartments were investigated, and samples analysed through FPA-µFTIR-Imaging spectroscopy followed by automatic analyses down to 11 µm particle size. All samples were contaminated with microplastics, with concentrations between 1.7 and 16.2 particles m-3. Synthetic fragments and fibres accounted, on average, for 4% of the total identified particles, while nonsynthetic particles of protein and cellulose constituted 91% and 4%, respectively. Polyester was the predominant synthetic polymer in all samples (81%), followed by polyethylene (5%), and nylon (3%). Microplastics were typically of smaller size than nonsynthetic particles. As the identified microplastics can be inhaled, these results highlight the potential direct human exposure to microplastic contamination via indoor air.

Short-range airborne transmission of expiratory droplets between two people

The occurrence of close proximity infection for many respiratory diseases is often cited as evidence of large droplet and/or close contact transmission. We explored interpersonal exposure of exhaled droplets and droplet nuclei of two standing thermal manikins as affected by distance, humidity, ventilation, and breathing mode. Under the specific set of conditions studied, we found a substantial increase in airborne exposure to droplet nuclei exhaled by the source manikin when a susceptible manikin is within about 1.5 m of the source manikin, referred to as the proximity effect. The threshold distance of about 1.5 m distinguishes the two basic transmission processes of droplets and droplet nuclei, that is, short-range modes and the long-range airborne route. The short-range modes include both the conventional large droplet route and the newly defined short-range airborne transmission. We thus reveal that transmission occurring in close proximity to the source patient includes both droplet-borne (large droplet) and short-range airborne routes, in addition to the direct deposition of large droplets on other body surfaces. The mechanisms of the droplet-borne and short-range airborne routes are different; their effective control methods also differ. Neither the current droplet precautions nor dilution ventilation prevents short-range airborne transmission, so new control methods are needed.

Protected zone ventilation and reduced personal exposure to airborne cross-infection

The main objective of this study was to examine the performance of protected zone ventilation (PZV) and hybrid protected zone ventilation (HPZV) to reduce the direct exposure to exhaled air from others' breathing. Experimental measurements are carried out to test the performance of PZV in a full-scale office room with two breathing thermal manikins. The measurements were performed under three configurations, including two standing manikins at different distances: 0.35, 0.5, and 1.1 m. When the supply air velocity is increased to 4 m/s in the downward plane jet, the dimensionless concentration is 40% lower than for fully mixed ventilation, which can be considered as a measure of protection from the zoning condition. The measurement results showed that in both the PZV and the HPZV system it is possible to decrease the transmission of tracer gas from one manikin to the opposite manikin; therefore, it probably would reduce the risk of air borne cross-infection between two people at the same relative positions. The results suggest that PZV and HPZV may be used to reduce the exposure of people in a protected zone from indoor pollutants emitted in a source zone.

Influence of air stability and metabolic rate on exhaled flow

The characteristics of contaminant transport and dispersion of exhaled flow from a manikin are thoroughly studied in this article with respect to the influence of two important factors: air stability conditions and metabolic rates. Four cases with the combinations of stable and neutral conditions as well as lower (1.2 met) and higher (2 met) metabolic rates for a breathing thermal manikin are employed. The exhaled contaminant is simulated by smoke and N2 O to visualize and measure the contaminant distribution both around and in front of the manikin. The results show that the microenvironment around the manikin body can be affected by different air distribution patterns and metabolic heating. Under stable conditions, the exhaled contaminant from mouth or nose is locked and stratified at certain heights, causing potentially high contaminant exposure to others. In addition, velocity profiles of the pulsating exhaled flow, which are normalized by mean peak velocities, present similar shapes to a steady jet. The outlet velocity close to the mouth shows decrement with both exhalation temperature and body plume. The velocity decay and concentration decay also show significant dependence on air stability and metabolic level.

Measuring the exhaled breath of a manikin and human subjects

Due to scarcity of accurate information and available data of actual human breathing, this investigation focuses on characterizing the breathing dynamic process based on the measurement of healthy human subjects. The similarities and differences between one breathing thermal manikin and the human subjects, including geometry and breathing functions, were thoroughly studied. As expected, actual human breathing is more complicated than that of the manikin in terms of airflow fluctuations, individual differences, and exhaled flow directions. The simplification of manikin mouth structure could result in overestimated exhaled velocity and contaminant concentration. Furthermore, actual human breathing appears to be relatively stable and reproducible for an individual person in several conditions and is also accompanied by some uncertainties simultaneously. The averaged values are used to analyze the overall characteristics of actual human breathing. There are different characteristics of the exhaled breath between male and female subjects with or without wearing a nose clip. The experimental results obtained from the measurement of human subjects may be helpful for manikin specification or validation and accuracy assessment of CFD simulations.

Measuring the exhaled breath of a manikin and human subjects

Due to scarcity of accurate information and available data of actual human breathing, this investigation focuses on characterizing the breathing dynamic process based on the measurement of healthy human subjects. The similarities and differences between one breathing thermal manikin and the human subjects, including geometry and breathing functions, were thoroughly studied. As expected, actual human breathing is more complicated than that of the manikin in terms of airflow fluctuations, individual differences, and exhaled flow directions. The simplification of manikin mouth structure could result in overestimated exhaled velocity and contaminant concentration. Furthermore, actual human breathing appears to be relatively stable and reproducible for an individual person in several conditions and is also accompanied by some uncertainties simultaneously. The averaged values are used to analyze the overall characteristics of actual human breathing. There are different characteristics of the exhaled breath between male and female subjects with or without wearing a nose clip. The experimental results obtained from the measurement of human subjects may be helpful for manikin specification or validation and accuracy assessment of CFD simulations.

Predictors for PaO2 and hypoxemic respiratory failure in COPD-A three-year follow-up

BACKGROUND

Knowledge about predictors for developing hypoxemia in the course of chronic obstructive pulmonary disease (COPD) progression is limited. The objective of the present study was to investigate predictors for overall PaO2, for a potential change in PaO2 over time, and for first occurrence of hypoxemia.

METHODS

419 patients aged 40-76 years with COPD GOLD stages II-IV underwent clinical and pulmonary function measurements, including repeated arterial blood gases over three years. Airway obstruction, lung hyperinflation, markers of systemic inflammation and cardiovascular health, exacerbation frequency, smoking habits, and body composition were tested as possible predictors of PaO2 and first episode of hypoxemia.

RESULTS

In multivariate adjusted longitudinal analyses, forced expiratory volume in 1 second, total lung capacity and functional residual capacity (all in% predicted), resting heart rate and fat mass index were all associated with overall PaO2 (all P < 0.005). We found no change in PaO2 over time (ρ = 0.33), nor did we find evidence that any of the tested variables predicted change in PaO2 over time. In multivariate adjusted survival analyses, functional residual capacity and resting heart rate were predictors of episodic hypoxemia (both ρ < 0.005).

CONCLUSIONS

This longitudinal study identified pulmonary, cardiac and metabolic risk factors for overall PaO2 and episodic hypoxemia, but detected no change in PaO2 over time.

Water condensation: a multiscale phenomenon

The condensation of water is a phenomenon occurring in multiple situations in everyday life, e.g., when fog is formed or when dew forms on the grass or on windows. This means that this phenomenon plays an important role within the different fields of science including meteorology, building physics, and chemistry. In this review we address condensation models and simulations with the main focus on heterogeneous condensation of water. The condensation process is, at first, described from a thermodynamic viewpoint where the nucleation step is described by the classical nucleation theory. Further, we address the shortcomings of the thermodynamic theory in describing the nucleation and emphasize the importance of nanoscale effects. This leads to the description of condensation from a molecular viewpoint. Also presented is how the nucleation can be simulated by use of molecular models, and how the condensation process is simulated on the macroscale using computational fluid dynamics. Finally, examples of hybrid models combining molecular and macroscale models for the simulation of condensation on a surface are presented.

The risk of airborne cross-infection in a room with vertical low-velocity ventilation

Downward flow ventilation systems are one of the most recommended ventilation strategies when contaminants in rooms must be removed and people must be protected from the risk of airborne cross-infection. This study is based on experimental tests carried out in a room with downward flow ventilation. Two breathing thermal manikins are placed in a room face to face. One manikin's breathing is considered to be the contaminated source to simulate a risky situation with airborne cross-infection. The position of the manikins in relation to the diffuser and the location of diffuser in the room as well as the distance between the manikins are being changed to observe the influence of these factors on the personal exposure of the target manikin. The results show that the DWF in different situations often is unable to penetrate the microenvironment generated by the manikins. The downward ventilation system can give an unexpected high level of contaminant exposure of the target manikin, when the distance between the manikins is reduced.

PRACTICAL IMPLICATIONS

Several guidelines recommend the downward ventilation system to reduce the risk of cross-infection between people in hospital rooms. This study shows that this recommendation should be taken into careful consideration. It is important to be aware of people position, position to other thermal loads in the room, and especially be aware of the distance between people if the exposure to the exhaled contaminants wants to be reduced.

Distribution of exhaled contaminants and personal exposure in a room using three different air distribution strategies

The level of exposure to human exhaled contaminants in a room depends not only on the air distribution system but also on people's different positions, the distance between them, people's activity level and height, direction of exhalation, and the surrounding temperature and temperature gradient. Human exhalation is studied in detail for different distribution systems: displacement and mixing ventilation as well as a system without mechanical ventilation. Two thermal manikins breathing through the mouth are used to simulate the exposure to human exhaled contaminants. The position and distance between the manikins are changed to study the influence on the level of exposure. The results show that the air exhaled by a manikin flows a longer distance with a higher concentration in case of displacement ventilation than in the other two cases, indicating a significant exposure to the contaminants for one person positioned in front of another. However, in all three cases, the exhalation flow of the source penetrates the thermal plume, causing an increase in the concentration of contaminants in front of the target person. The results are significantly dependent on the distance and position between the two manikins in all three cases.

PRACTICAL IMPLICATIONS

Indoor environments are susceptible to contaminant exposure, as contaminants can easily spread in the air. Human breathing is one of the most important biological contaminant sources, as the exhaled air can contain different pathogens such as viruses and bacteria. This paper addresses the human exhalation flow and its behavior in connection with different ventilation strategies, as well as the interaction between two people in a room. This is a key factor for studying the airborne infection risk when the room is occupied by several persons. The paper only takes into account the airborne part of the infection risk.

Dietary antioxidants and forced expiratory volume in 1 s decline: the Health, Aging and Body Composition study

Increased antioxidant defences are hypothesised to decrease age- and smoking-related decline in lung function. The relationship between dietary antioxidants, smoking and forced expiratory volume in 1 s (FEV(1)) was investigated in community-dwelling older adults in the Health, Aging and Body Composition study. 1,443 participants completed a food frequency questionnaire, self-reported smoking history and had measurements taken of FEV(1) at both baseline and after 4 yrs of follow-up. The association of dietary intake of nutrients and foods with antioxidant properties and rate of FEV(1) decline was investigated using hierarchical linear regression models. In continuing smokers (current smokers at both time-points), higher vitamin C intake and higher intake of fruit and vegetables were associated with an 18 and 24 mL · yr(-1) slower rate of FEV(1) decline compared with a lower intake (p < 0.0001 and p = 0.003, respectively). In quitters (a current smoker at study baseline who had quit during follow-up), higher intake was associated with an attenuated rate of decline for each nutrient studied (p ≤ 0.003 for all models). In nonsmoking participants, there was little or no association of diet and rate of decline in FEV(1). The intake of nutrients with antioxidant properties may modulate lung function decline in older adults exposed to cigarette smoke.

Using the lower limit of normal for the FEV1/FVC ratio reduces the misclassification of airway obstruction

AIM

The prevalence of airway obstruction varies widely with the definition used.

OBJECTIVES

To study differences in the prevalence of airway obstruction when applying four international guidelines to three population samples using four regression equations.

METHODS

We collected predicted values for forced expiratory volume in 1 s/forced vital capacity (FEV(1)/FVC) and its lower limit of normal (LLN) from the literature. FEV(1)/FVC from 40 646 adults (including 13 136 asymptomatic never smokers) aged 17-90+years were available from American, English and Dutch population based surveys. The prevalence of airway obstruction was determined by the LLN for FEV(1)/FVC, and by using the Global Initiative for Chronic Obstructive Lung Disease (GOLD), American Thoracic Society/European Respiratory Society (ATS/ERS) or British Thoracic Society (BTS) guidelines, initially in the healthy subgroup and then in the entire population.

RESULTS

The LLN for FEV(1)/FVC varied between prediction equations (57 available for men and 55 for women), and demonstrated marked negative age dependency. Median age at which the LLN fell below 0.70 in healthy subjects was 42 and 48 years in men and women, respectively. When applying the reference equations (Health Survey for England 1995-1996, National Health and Nutrition Examination Survey (NHANES) III, European Community for Coal and Steel (ECCS)/ERS and a Dutch population study) to the selected population samples, the prevalence of airway obstruction in healthy never smokers aged over 60 years varied for each guideline: 17-45% of men and 7-26% of women for GOLD; 0-18% of men and 0-16% of women for ATS/ERS; and 0-9% of men and 0-11% of women for BTS. GOLD guidelines caused false positive rates of up to 60% when applied to entire populations.

CONCLUSIONS

Airway obstruction should be defined by FEV(1)/FVC and FEV(1) being below the LLN using appropriate reference equations.

Effects of drag factor on physiological aspects of rowing

This study examined the effects of two resistances, or "drag factors" on selected physiological variables during incremental progressive rowing tests (seven 3-min stages) on a Concept2 ergometer. Subjects were seven male and seven female university club rowers. Their mean age, body mass and height were 19.6 +/- 1.5 years, 72.7 +/- 8.0 kg, and 172.2 +/- 7.5 cm, respectively. Progressive tests were conducted using drag factors 100 (D100) and 150 (D150) before the spring racing season. Values were determined for the following physiological variables: ventilation (V.E), oxygen uptake (V.O2), heart rate (HR), blood lactate concentration (BLC), respiratory exchange ratio (R) and rowing economy (W/V.O2). Comparisons across all six submaximal stages showed no significant difference between D(100) and D(150) for any of the variables measured (p > .05). Maximal V.E(max) was significantly greater at D100 than D150 (p < .02). Maximal V.O(2), HR, BLC, R, stroke rate (SR) and W/V.O2 were greater at D100 than at D150, though not significantly so. The mean D100-D150 differences in V.E and SR for each stage were significantly correlated (r = 0.76, p < .01), suggesting drag factor may affect V.E via SR.

Limitations in the use of Drosophila melanogaster as a model host for gram-positive bacterial infection

AIMS

To examine sensitivities of various Drosophila melanogaster strains towards human pathogenic and nonpathogenic gram-positive bacteria.

METHODS AND RESULTS

The D. melanogaster Oregon R strain was infected by injecting the thorax with a needle containing Escherichia coli (negative control), Listeria monocytogenes, Staphylococcus aureus (both food-borne pathogens), Listeria innocua, Bacillus subtilis, Carnobacterium maltaromaticum, Lactobacillus plantarum or Pediococcus acidilactici (all nonpathogenic bacteria). Listeria monocytogenes and S. aureus killed the host rapidly compared with the negative control. Infection with L. innocua, B. subtilis or C. maltaromaticum also resulted in a high fly mortality, whereas Lact. plantarum and P. acidilactici resulted in a slightly increased mortality. Four additional D. melanogaster lines, three of which had been selected for heat, cold and desiccation resistance respectively, were subjected to infection by L. monocytogenes, S. aureus and E. coli. Mortality rates were comparable with that of the Oregon R strain.

CONCLUSIONS

Use of the injection method shows the limitation of D. melanogaster as a model host for gram-positive bacteria as opportunistic infection by nonpathogenic gram-positive bacteria results in partial or high mortality. In addition, lines of fruit flies resistant to various stress exposures did not show an increased resistance to infection by gram-positive pathogens under the conditions tested.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study demonstrates the inadequacy of D. melanogaster infected by the injection method in order to distinguish between virulent and nonvirulent gram-positive bacteria.

Early pathologic findings and long-term improvement in anti-Ma2-associated encephalitis

A 67-year-old man sequentially developed anti-Ma2-associated paraneoplastic encephalitis (PNE) and contralateral herpes simplex encephalitis (HSE). Brain biopsy 1 month before HSE revealed extensive infiltrates of T cells, B cells, and plasma cells. Most T cells expressed the cytotoxic granule-associated protein TIA-1 and the membranolytic protein granzyme-B. Although recovery was thought to be unlikely, treatment of the PNE with corticosteroids and resection of the associated lung cancer resulted in dramatic improvement for 21 months.

Energy expenditure, heart rate response, and metabolic equivalents (METs) of adults taking part in children's games

AIM

The needs of physical activity can be seen through the lack of numbers participating in regular physical activity as well as the increase in prevalence of certain diseases such as Type II diabetes (especially in children), cardiovascular diseases, and some cancers. With the increase in preventable diseases that are caused in part by a sedentary lifestyle, a closer look needs to be taken into the role of family interaction as a means of increasing physical activity for both adults and children. Because of the many benefits of physical activity in relation to health, a family approach to achieving recommended levels of physical activity may be quite applicable.

METHODS

Forty volunteers were recruited from the community (20 subjects and 20 children). The volunteers played 2 games: soccer and nerfball. Data was collected over 10 minutes (5 min per game). Expired air analysis was used to calculate energy expenditure and metabolic equivalents (METs). Descriptive statistics were calculated along with a regression analysis to determine differences between the 2 games, and an ACOVA to determine any significant effects of age, child age, gender, and physical activity level on the results.

RESULTS

For both games, average heart rate measured approximately 88%max; average METs measured approximately 6, average energy expenditure measured approximately 40 kcal.

CONCLUSIONS

S: This study showed that adults can achieve recommended physical activity levels through these specific activities if sustained for approximately 20 min.

Effects of dietary supplementation with vitamins C and E on muscle function during and after eccentric contractions in humans

Reactive oxygen species may contribute to exercise-induced skeletal muscle damage, and antioxidants may protect against such damage. This study examined the effectiveness of prophylactic supplementation with vitamins C and E on symptoms of muscle damage in a single blind, two-group study design. Twelve male volunteers were randomly assigned to either treatment or control groups. The treatment group received 500 mg of vitamin C and 1,200 IU of alpha-tocopherol daily and the control group received glucose placebo for 37 days. After 30 days of treatment, volunteers performed 300 maximal eccentric contractions of the knee extensor muscles of one leg. Maximal voluntary isometric contraction force and electrically evoked force at a frequency of 20 Hz and 50 Hz were recorded before and after exercise, and on days 1, 2 and 7 after exercise. Muscle soreness questionnaires were completed and muscle girth recorded at the same time points. Eccentric contractile torque and work during the bout declined significantly in both groups ( P<0.001), but this decline was smaller in the vitamin-supplemented group ( P<0.05). Maximal voluntary isometric contraction force and 20:50 Hz force ratio declined significantly after exercise in both groups ( P<0.01), but the decline was smaller in the treatment group on days 1 and 2 post-exercise ( P<0.05). Both groups experienced similar significant muscle soreness and swelling after exercise. These data suggest that prior supplementation with dietary antioxidants ameliorates muscle functional decrements subsequent to eccentric muscle contraction.

Endoscopic-assisted craniofacial resection of esthesioneuroblastoma: minimizing facial incisions--technical note and report of 3 cases

The surgical management of esthesioneuroblastoma with anterior skull base involvement has traditionally been craniofacial resection, which combines a bifrontal craniotomy with a transfacial approach. The latter usually involves a disfiguring facial incision, mid-facial degloving, lateral rhinotomy, and/or extensive facial osteotomies, which may be cosmetically displeasing to the patient. The advent of angled endoscopes has provided excellent magnification and illumination for surgeons to remove tumors using minimally invasive techniques. The authors describe their experience with three cases of esthesioneuroblastoma, which were surgically removed using a transnasal endoscopic approach, avoiding transfacial incisions. Preoperative radiographs were reviewed and tumors were staged according to the Kadish staging system. One patient had a recurrent esthesioneuroblastoma (Kadish stage B), which was removed entirely through a transnasal endoscopic approach. Two patients had intracranial extension (Kadish stage C), which were resected with a combined approach, endoscopically from below and a bifrontal craniotomy from above, to remove intracranial disease. All patients underwent reconstruction of the anterior skull base. Esthesioneuroblastomas confined to the nasal and paranasal cavities (Kadish stage A and B) were readily accessible through the transnasal endoscopic approach. If there was significant intracranial disease (Kadish stage C), adding a bifrontal craniotomy provided excellent exposure for complete resection of involved tumor. All patients underwent complete tumor resection with negative margins. None developed a cerebrospinal fluid (CSF) leak. The endoscopic-assisted craniofacial approach for the surgical management of esthesioneuroblastomas provides excellent exposure, adequate visualization, and the cosmetic benefit of avoiding an external facial incision.

Airway inflammation in COPD: physiological outcome measures and induced sputum

Chronic obstructive pulmonary disease (COPD) is a result of airway inflammation, and the best predictor of COPD is the early detection of airflow limitation by spirometry. The Global Initiative for Obstructive Lung Disease Workshop Report defines airflow limitation using simple spirometric indices. Available guidelines categorise the severity of COPD using forced expiratory volume in one second (FEV1) and forced vital capacity (FVC), with symptoms playing a minor role in the assessment. Current standards define COPD by progressive loss of FEV1, and thus longitudinal decline in FEV1 will be the primary outcome variable for intervention studies aimed at preventing or reducing the loss of pulmonary function. There is evidence, however, that the variable FEV1/FVC and FEV1 are often not measured properly in all settings. This article will discuss the roles of physiological measurements in diagnosing COPD and physiological outcome measures for COPD. It does not formally compare physiological measures with other outcome measures, such as symptoms or quality of life. Additionally, improved treatment of established disease requires a better understanding of the inflammatory process and its clinical effects and treatment. The inflammatory process, and how drugs affect it, can be studied noninvasively or relatively noninvasively by using refined methods of examining spontaneous or induced sputum. Enhanced understanding of the use of induced sputum will assist in predicting patients' responses to short- and long-term inhaled corticosteroid treatment, and the methods of sputum examination need to be simplified so that they can be applied more easily to clinical practice.

Single-breath carbon monoxide diffusing capacity

Measurement of DL(CO) remains a clinically useful way to assess transfer of gases across the lung. It is important, however, to be vigilant in controlling the sources of variation and to be aware of those that remain when interpreting the measured values.

Airflow limitation is underrecognized in well-functioning older people

OBJECTIVES

Dyspnea is a common symptom in older people. A reduced forced expiratory volume in 1 second (FEV1) is associated with a higher mortality rate from cardiovascular and respiratory disease, and increased admissions to hospitals. Underrecognized or undertreated airflow limitation may exacerbate the problem. The purpose of this study was to assess the prevalence and treatment of airflow limitation in a cohort of well-functioning older people.

DESIGN

Cross-sectional study.

SETTING

Baseline of a clinical-epidemiological study of incident functional limitation.

PARTICIPANTS

Participants attended the baseline examination of the Health, Aging, and Body Composition study, a prospective cohort study of 3,075 well-functioning subjects age 70 to 79.

MEASUREMENTS

Demographic and clinical data were collected by interview. Spirometry was performed unless contraindicated and repeated until three acceptable sets of flow-volume loops were obtained. Patients on bronchodilator medications had spirometry performed posttherapy. Blinded readers assessed the flow-volume loops, and inadequate tests were omitted from analysis. Airflow limitation was defined as a reduced forced expiratory volume in 1 second/forced vital capacity (FEV1/FVC) as determined by age-, sex-, and race-normalized values. Severity of airflow limitation was defined by American Thoracic Society criteria.

RESULTS

Two thousand four hundred eighty-five subjects (80.8%) had assessable spirometry and data on treatment and diagnosis (1,265 men, 1,220 women). The mean age was 73.6 years. Two hundred sixty-two subjects (10.5%) had airflow limitation; 43 (16.4%) of these never smoked. Only 37.4% of participants with airflow limitation and 55.6% of participants with severe airflow limitation reported a diagnosis of lung disease. Only 20.5% of subjects with at least moderate airflow limitation had used a bronchodilator in the previous 2 weeks.

CONCLUSION

Despite their good functional status, airflow limitation was present, and underrecognized, in a considerable proportion of our older population. The low bronchodilator use suggests a significant reservoir of untreated disease. Physicians caring for older people need to be more vigilant for both the presence, and the need for treatment, of airflow limitation.

Calcium channel antagonists inhibit growth of subcutaneous xenograft meningiomas in nude mice

BACKGROUND

We have previously shown that calcium channel antagonists inhibit in vitro meningioma growth. This study examines the effect of calcium channel antagonists on in vivo xenograft meningioma growth.

METHODS

Meningioma cells taken from human patients were mixed with Matrigel and injected into the subcutaneous space in the flank of nude mice. These animals were treated with calcium channel antagonists in their drinking water. Tumor volumes were measured over time; comparison was made between control and treatment groups. Daily weights, average daily water consumption, and serum calcium channel antagonist levels were determined. Comparison of histology and proliferation index was made between control and treatment groups.

RESULTS

Diltiazem treatment decreased tumor growth over time compared to control groups. Increased tumor growth inhibition was seen with increasing doses (p > 0.05). Treatment with verapamil had similar effects; however, there are no statistically significant dose dependent decreases in growth with increasing verapamil doses. There were no tumor "cures" or spontaneous regression of tumor in any group including the control groups. Animal daily weight and average daily water consumption was unaffected by increasing calcium channel antagonist doses compared to control groups. Mouse serum drug levels increased with increasing doses of drug in the drinking water of treatment groups (p > 0.05). Histology and proliferative index of treatment groups were similar to control groups.

CONCLUSION

Calcium channel antagonists decrease but do not completely inhibit the growth of meningiomas in nude mice. Clinical correlations and potential applications are discussed.

A simple diagnostic index for asthma

BACKGROUND

Asthma is becoming increasingly prevalent and a number of research groups are investigating its genetic and environmental basis.

OBJECTIVE

To produce a brief screening tool suitable for determining phenotype in asthma research.

METHODS

The scores from eight questions on symptoms and history were obtained from 678 adults and 244 children from high asthma-incidence caucasian families. An independent physician diagnosis was also obtained with the use of a modified NHLBI-CSGA questionnaire and pulmonary function test. Stepwise logistic regression was applied to determine which of the eight questions had greatest predictive value for asthma, and the quality of the resultant models was evaluated using an independent set of 643 adults and 239 children.

RESULTS

For adults, the most parsimonious model used responses from three of the eight questions. It had sensitivity and specificity of 0.94 and 0.96, respectively. For children, responses to two questions gave a model with sensitivity and specificity of 0.97. For both age groups, negative predictive values were above 0.87. Positive predictive values were 0.58 and 0.78 for adults and children respectively. The latter emphasize the need for conformation, by physician, of "affected" calls made by this initial screen.

CONCLUSION

The brief questionnaires described are potentially useful in a research setting, as a preliminary screening mechanism of low cost. Their use will reduce the numbers of subjects that must undergo detailed phenotyping.

Influence of leisure time physical activity and television watching on atherosclerosis risk factors in the NHLBI Family Heart Study

Physical activity favorably influences atherosclerosis risk factors but only a few studies in adults considered the time watching television (TV) as a measure of physical inactivity. We therefore determined in a population-based sample of 1778 subjects from the NHLBI Family Heart Study (FHS) whether leisure time physical activity and TV watching have independent or interactive associations with cardiovascular disease risk factors and carotid artery intima-media wall thickness (IMT). Subjects were free from diabetes mellitus and clinically-ascertained coronary artery disease and did not take lipid-lowering or antihypertensive drugs. Only 0.7 and 1.3% of the variance in leisure time physical activity in women and men, respectively, was explained by the amount of TV watching. Leisure time physical activity had a clearly favorable, and TV watching an unfavorable association with anthropometric measurements (BMI (body mass index), waist girth, waist-hip ratio, subscapular and triceps skinfold thickness). The odds ratio (95% CI) of being overweight was 0.41 (0.28-0.62) in women and 0.69 (0.46-1.04) in men in the highest quartile of leisure time physical activity compared to the lowest quartile. The odds ratio increased for increasing quartiles of TV watching to 2.12 (1.45-3.10) in women and 1.61 (1.07-2.43) in men. Watching TV only 1 h per day in women with a BMI of 30 kg/m2 and doing about 75 min of moderate exercise per week was associated with a BMI 1.8 kg/m2 lower than in women watching TV 3 h per day and doing the same amount of exercise. Those with twice the amount of moderate exercise and watching TV 1 h per day had a BMI 0.45 kg/m2 lower. Furthermore, leisure time physical activity was negatively associated with concentrations of triglycerides and positively with HDL cholesterol in both genders. TV watching was significantly positively associated with triglycerides and slightly negatively with HDL cholesterol in men. The observed associations of leisure time physical activity and TV watching with atherosclerosis risk factors were independent from each other. Finally, we analyzed the relation between leisure time physical activity, TV watching and the degree of IMT of the carotid arteries. Neither of these two measures was significantly associated with IMT. In summary, TV watching, in addition to leisure time physical activity, shows an independent association with obesity-related anthropometric measurements, HDL and triglycerides. Decreasing the amount of TV watching might be effective as a first step in reducing atherosclerosis risk factors, especially overweight.

Nasal continuous positive airway pressure devices do not maintain the set pressure dynamically when tested under simulated clinical conditions

STUDY OBJECTIVES

Nasal continuous positive airway pressure (CPAP) is standard therapy for obstructive sleep apnea syndrome. The effective nasal mask pressure may be adversely affected by factors that increase system resistance (eg, long tubing and/or water condensation) and by dynamic variables (breathing frequency [f] and tidal volume [VT]). The present study was conducted in order to assess the performance of CPAP machines throughout a range of simulated clinical conditions.

DESIGN

Four currently used CPAP machines were tested at settings of 5, 10, 15, and 20 cm H(2)O using a pulmonary waveform generator to produce VTs of 0.4, 0.8, and 1.2 L at frequencies of 10, 20, and 30 breaths/min. Machines were tested under five conditions: 6-foot and 12-foot tubing, with and without an in-line humidifier, and 12-foot tubing with humidifier and water condensation.

MEASUREMENTS

Maximum and minimum mask pressure measurements were obtained during five respiratory cycles for each dynamic variable under each of the five conditions and CPAP settings (180 experiments on each of four CPAP models).

RESULTS

Using typical clinical parameters (VT, 0.4 L and 0.8 L; f, 10 breaths/min and 20 breaths/min; and CPAP, 5 to 15 cm H(2)O), mask pressure consistently varied above and below the set point when additional tubing and/or a humidifier were added to the system (0.7 to 2.9 cm H(2)O below and 0.5 to 1.0 cm H(2)O above the set pressure). Water condensation caused large pressure deviations (inspiratory pressure ranged from 3.5 to 5.6 cm H(2)O below set pressure, and expiratory pressure ranged from 0.7 to 3.5 cm H(2)O above set pressure).

CONCLUSIONS

Therapy and compliance could be adversely affected because some CPAP machines in current use do not maintain constant continuous mask pressure when tested using simulated conditions, especially when water condenses in the tubing.

Role of topical steroids in reducing dysfunction after nerve injury

OBJECTIVE

To determine the efficacy of topical dexamethasone in reducing nerve dysfunction after axonotmesis injury.

STUDY DESIGN

A three-armed, blinded study including sham, control, and test groups was designed using the rat sciatic nerve crush injury model.

METHODS

Twenty-two rats were randomly assigned to a control group or a topical steroid group. A standardized sciatic nerve crush injury was performed under sterile conditions on each animal. A separate group of five rats underwent a sham operation to isolate the crush injury as the source of postoperative dysfunction in the control and steroid groups. All animals underwent walking track analysis with calculation of the sciatic functional index (SFI) before surgery and through the postoperative recovery period. Dexamethasone saturated Gelfoam was placed at the site of injury in the topical steroid group. The functional performance of each group was compared throughout the recovery period.

RESULTS

No morbidity associated with topical application of steroids at the injury site was noted. The topical steroid group had improved recovery at postoperative days 14, 18, and 22. This difference was statistically significant at day 14. At the termination of the study, there was a clear trend toward superior recovery for the steroid group compared with controls (90% vs. 73%), but this difference did not reach statistical significance.

CONCLUSIONS

Clinical use of topical steroids to reduce postoperative nerve dysfunction warrants further study.

FEV(6) is an acceptable surrogate for FVC in the spirometric diagnosis of airway obstruction and restriction

We analyzed the FEV(1)/FEV(6) and FEV(1)/FVC results of 502 consecutive patients in the spirometric diagnosis of airway obstruction. We also examined the agreement between FEV(6) and FVC in the spirometric diagnosis of restriction. Technically acceptable test results were obtained from 337 subjects (67%). The sensitivity of FEV(1)/FEV(6) for diagnosing airway obstruction as defined by FEV(1)/ FVC was 95.0%; the specificity was 97.4%. When interpretations differed, the measured values were all close to the lower limits of the reference ranges. When analysis included +/- 100-ml variability in FEV(1) and FEV(6), the sensitivity increased to 99.5% and the specificity to 100%. The reproducibility of FEV(6) was superior to that of FVC. These results suggest that FEV(6) is an accurate, reliable alternative to FVC for diagnosing airway obstruction and that FEV(6) is reasonably comparable to FVC for the spirometric diagnosis of restriction. FEV(6) is more reproducible and less physically demanding for patients.

The accuracy of pulse oximetry in the emergency department

The objective of this retrospective study was to identify factors affecting the accuracy of pulse oximetry in the ED. Over a 3-year period, 664 consecutive emergency department (ED) patients had simultaneous arterial blood gas (ABG) and pulse oximeter readings taken. Pulse oximeter saturations (SpO2) were compared with ABG CO-oximeter saturations (SaO2) for accuracy. Multiple variables including age, sex, hemoglobin, bicarbonate, pH, and carboxyhemoglobin (COHb) were analyzed to see if they affected SpO2 accuracy. ROC curves were used to determine the best pulse oximeter threshold for detecting hypoxia. Using multivariate analysis, COHb was the only statistically significant factor affecting the accuracy of pulse oximetry. In patients with COHb <2%, SpO2 overestimated SaO2 by more than 4% in 8.4% of cases. In patients with COHb > or = 2%, SpO2 overestimated SaO2 by more than 4% in 35% of cases. The best pulse oximetry threshold for detecting hypoxia is 92%. At this threshold, if COHb is <2%, pulse oximetry has a sensitivity of 0.92 and specificity of 0.90. If COHb is > or =2%, sensitivity is 0.74 and specificity is 0.84. For patients likely to have a COHb < 2, pulse oximetry is an effective screening tool for detecting hypoxia. However, more caution must be exercised when using pulse oximetry in patients likely to have a COHb > or = 2%.

Calcium channel antagonist effect on in vitro meningioma signal transduction pathways after growth factor stimulation

OBJECTIVE

We have previously demonstrated that calcium channel antagonists inhibit the growth of human meningiomas in culture after stimulation with growth factors. This study examined the effects of these drugs on signaling transduction pathways in an attempt to elucidate potential mechanisms by which this growth inhibition is mediated.

METHODS

Primary cell cultures from patients with intracranial meningiomas were established. Cell growth studies were performed with inhibitors and stimulators of tyrosine kinase signal transduction. Intracellular calcium changes and inositol phosphate production were measured after growth factor exposure, with or without pretreatment by calcium channel antagonists.

RESULTS

The growth of meningiomas in culture can be inhibited by tyrosine kinase receptor inhibitors. Inhibitors and stimulators of phospholipase C can stimulate or inhibit the growth of in vitro meningiomas, respectively. Calcium channel antagonists inhibit intracellular calcium changes induced by serum and epidermal growth factor. Inositol phosphate production is increased after growth factor stimulation, and calcium channel antagonists potentiate this effect.

CONCLUSION

Calcium channel antagonists interfere with intracellular signaling pathways of cultured meningioma cells. This inhibition is unrelated to voltage-sensitive calcium channels. The findings of this project may aid in the understanding of the signal transduction mechanisms involved in growth factor-mediated meningioma proliferation and may lead to clinically relevant strategies for growth inhibition.

Arterial blood gas reference values for sea level and an altitude of 1,400 meters

Blood gas measurements were collected on healthy lifetime nonsmokers at sea level (n = 96) and at an altitude of 1,400 meters (n = 243) to establish reference equations. At each study site, arterial blood samples were analyzed in duplicate on two separate blood gas analyzers and CO-oximeters. Arterial blood gas variables included Pa(O(2)), Pa(CO(2)), pH, and calculated alveolar-arterial PO(2) difference (AaPO(2)). CO-oximeter variables were Hb, COHb, MetHb, and Sa(O(2)). Subjects were 18 to 81 yr of age with 166 male and 173 female. Outlier data were excluded from multiple regression analysis, and reference equations were fitted to the data in two ways: (1) best fit using linear, squared, and cross-product terms; (2) simple equations, including only the variables that explained at least 3% of the variance. Two sets of equations were created: (1) using only the sea level data and (2) using the combined data with barometric pressure as an independent variable. Comparisons with earlier studies revealed small but significant differences; the decline in Pa(O(2)) with age at each altitude was consistent with most previous studies. At sea level, the equation that included barometric pressure predicted Pa(O(2)) slightly better than the sea level specific equation. The inclusion of barometric pressure in the equations allows better prediction of blood gas reference values at sea level and at altitudes as high as 1,400 meters.

Intraoperative electromyographic assessment of recurrent laryngeal nerve stress and pharyngeal injury during anterior cervical spine surgery with Caspar instrumentation

OBJECT

Recurrent laryngeal nerve (RLN) injury occurs after anterior cervical spine procedures. In this study the authors used intraoperative electromyographic (EMG) monitoring of the posterior pharynx as a surrogate for RLN function and monitored endotracheal tube (ET) cuff pressure to determine if there was an association between these variables and clinical outcome.

METHODS

Sixty patients in whom anterior cervical spine procedures were to be performed comprised the study population. After intubation, the ET cuff was adjusted to a just-seal volume and attached to a pressure monitor. A laryngeal surface electrode was placed in the posterior pharynx, and spontaneous EMG activity was monitored throughout the procedure. Cuff pressures and EMG activity were recorded during neck retraction and when EMG activity increased 20% above baseline. Patients were divided into two groups: those with sore throat/dysphonia and those without symptoms. Cuff pressures and EMG values were compared between groups, and the differences were correlated with clinical outcome.

CONCLUSIONS

Hoarseness immediately after surgery was reported in 38% of patients whereas 15% exhibited severe symptoms. In symptomatic patients the period of intubation had been longer, and the ET cuff pressures had been elevated. In most patients EMG activity increased during insertion of the retractor and decreased after its removal. In these patients a greater number of episodes of elevated EMG activity during surgery were also noted. Two patients experienced prolonged hoarseness, and one required teflon injections of the vocal fold. This patient's EMG activity increased (15-18 times baseline) during surgery. In the few patients who were symptomatic with increased EMG activity, neither the timing nor direction of change could be associated with symptoms. Intubation time and elevated ET cuff pressure were the most important contributors to dysphonia and sore throat after anterior cervical spine surgery.

Gonococcal infection of human fallopian tube mucosa in organ culture: relationship of mucosal tissue TNF-alpha concentration to sloughing of ciliated cells

BACKGROUND AND OBJECTIVES

An experimental model consisting of gonococcal infection of human fallopian tube mucosa in organ culture has proven useful in studying the molecular pathogenesis of acute gonococcal salpingitis and postsalpingitis sequelae. Gonococcal infection of human fallopian tube mucosa in organ culture results in the sloughing of ciliated epithelial cells from the mucosa. This damage to the mucosa can be quantified on fallopian tube pieces by an assay of the percent of the periphery that has ciliary activity (PPCA) remaining at specific time points after infection. Although assay of the PPCA has been quite valuable, it is labor-intensive, somewhat subjective, and requires that the observers have training and experience. A more practical assay for genital mucosal damage is desirable for further investigations that employ the fallopian tube experimental model. Gonococcal infection of fallopian tube mucosa in organ culture also results in the production of easily quantified tumor necrosis factor-alpha (TNF-alpha) by the mucosa. Furthermore, treatment of the organ cultures with recombinant human TNF-alpha (rHuTNFalpha) alone also causes sloughing of ciliated cells from the mucosa. These findings strongly suggest that TNF-alpha is a mediator of the mucosal damage that attends gonococcal infection.

GOALS OF THE STUDY

To determine: (1) whether the PPCA values and the TNF-alpha concentrations in fallopian tube mucosal tissues correlate closely enough to allow prediction of the PPCA from a measurement of the mucosal tissue TNF-alpha concentration; and (2) whether the correlation of the TNF-alpha mucosal tissue concentration with the sloughing of ciliated cells (measured by the PPCA) supports the hypothesis that induction of TNF-alpha by gonococcal infection, with resultant sloughing of ciliated cells, is likely to be a major pathogenic mechanism of gonococcal salpingitis and might mediate postsalpingitis infertility and ectopic pregnancy.

STUDY DESIGN

A metaanalysis was performed on studies from three research groups (two laboratories in the United States and one in the United Kingdom, using identical techniques for quantifying the PPCA, TNF-alpha, or both.

RESULTS

There was a close and statistically significant correlation between the TNF-alpha mucosal tissue concentration and the proportion of ciliated cells lost from the mucosa as measured by the PPCA (r = 0.95, p < 0.001). Therefore, as the mucosal tissue concentration of endogenous TNF-alpha increased, the loss of ciliated cells from the epithelium increased proportionately.

CONCLUSIONS

During gonococcal infection of human fallopian tube mucosa in organ culture, the mucosal tissue concentration of TNF-alpha can be used to predict the PPCA, and therefore, the extent of mucosal damage. This finding should facilitate studies of the molecular pathogenesis of infectious diseases involving human genital mucosa. Further, the close correlation of mucosal TNF-alpha concentration with genital mucosal damage, evaluated by the PPCA, supports the hypothesis that induction of the proinflammatory cytokine, TNF-alpha, by gonococcal infection, with resultant inflammation and sloughing of ciliated cells, is an important pathogenic mechanism of gonococcal salpingitis and may mediate postsalpingitis infertility and ectopic pregnancy as well.

Use of EMG analysis in challenging kinetic chain terminology

PURPOSE

The purpose of this study was to compare mean integrated electromyographic values (EMG(int)) during biomechanically comparable closed kinetic chain/fixed external load, open kinetic chain/moveable no load, and moveable external load exercises.

METHODS

EMG(int) were obtained for the pectoralis major (PM) and the long head of the triceps (T) during absorption and force phases of three biomechanically comparable exercises: the push-up (PU); the bench press-load (BP-L); and the bench press-no load (BP-NL) equated to the closed kinetic chain/fixed external load; moveable external load; and open kinetic chain/moveable no load conditions respectively. A force plate was used to equate load for the PU and BP-L exercises. Ten males (24+/-4.4 yr) participated in the three randomly ordered exercises. A pronated, closed grip was used for all exercises. The mean integrated EMG values from three isometric maximal voluntary contractions were used to determine a reference EMG (EMG(MVC)) for each muscle. Normalized EMG values (NEMG) were determined by EMG(int)/EMG(Mvc) and analyzed by one-factor repeated measures ANOVA for each muscle (PM and T) during each phase (absorption and force).

RESULTS

There was no significant difference (P > 0.05) between the equivalently loaded, different boundary exercises (PU and BP). Statistical significance (P < 0.05) was determined between the differently loaded, equivalent boundary exercises (BP and BP-NL) as well as the differently loaded, different boundary exercises (PU and BP-NL).

CONCLUSIONS

Results from this study support the theory that activities of similar biomechanical motions and mass of loading, regardless of the boundary condition, have comparable EMG values of primary muscle groups. In addition, this study suggests external load is more important than boundary condition in describing human activity.

Differences in spirometry reference values: a statistical comparison of a Mongolian and a Caucasian study

New reference value studies for spirometry are commonly compared to existing reference value studies using average data derived from existing reference equations. Such comparisons are inherently flawed because they do not account for differences in distributions of the independent and dependent variables and they do not have identical methodologies. This study was undertaken 1) to derive reference equations for forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) for natives of Mongolia and 2) to compare the Mongolian data with data from a 1981 reference study of Caucasians in Salt Lake City, UT, USA. Spirometry was performed on 344 (176 male, 168 female) healthy, nonsmoking urban natives of Mongolia to generate reference equations for FVC, FEV1, and FEV1/FVC. These data were compared with data from a 1981 reference study of Caucasians in Salt Lake City, using both an analysis of covariance of the raw data and parametric and nonparametric comparisons of a matched pair subset. Average measured forced vital capacity and forced expiratory volume in one second in native Mongolians were within 1-2% of the Caucasian predicted values. These small differences are not statistically significant in any of the multiple methods of comparisons. Power analysis suggests that, if real differences exist, the differences in forced vital capacity are <155 mL for males, <105 mL for females, and the differences in forced expiratory volume in one second are <107 mL for males and <76 mL for females.

[Primary pyogenic liver abscess in a child]

A case report describing a child with a primary pyogenic liver abscess is presented. Primary pyogenic liver abscess is a rare disease at this age. Furthermore the clinical picture only rarely reveals indications of liver disease. To establish the correct diagnosis within the proper time, one must remember this diagnostic possibility. The recommended treatment is shortly discussed.

Strength training for women: debunking myths that block opportunity

Traditional gender roles and differences in absolute strength have resulted in misconceived approaches to strength training for women. Male physiology, more than hormones, explains men's superior absolute strength. When other measures of strength are used, such as strength relative to cross-sectional area of muscle, the strength of men and women is nearly equal. Women who practice the same well-designed strength training programs as men benefit from bone and soft-tissue modeling, increased lean body mass, decreased fat, and enhanced self-confidence.

Growth factor-mediated angiogenesis in the malignant progression of glial tumors: a review

BACKGROUND

We review the role of peptide growth factors in angiogenesis and progression of low grade glial tumors to higher grade glioblastoma multiforme (GBM).

METHODS

Vascular pathology is a key feature of glioblastoma multiforme characterized by hypervascularity, vascular permeability, and hypercoagulability.

RESULTS

Vascular endothelial growth factor (VEGF) can mediate all of these effects, but by itself does not promote malignant growth. Epidermal growth factor (EGF), platelet-derived growth factor (PDGF), fibroblast growth factor (FGF), and transforming growth factor beta (TGF-beta) are implicated in the angiogenesis of a number of tumors including those of glial origin.

CONCLUSIONS

These growth factors are suggested to play a role in autocrine and/or paracrine mediated tumorogenesis of astrocytic tumors. VEGF secretion might be the product of induction by physiologic concentrations of other growth factors with VEGF being the common pathway of neovascularization and progression to GBM.

Matrigel augments xenograft transplantation of meningioma cells into athymic mice

OBJECTIVE

We investigated the use of Matrigel to enhance the growth of human meningiomas in athymic (nude) mice. Tumor take and growth of xenograft meningioma cells in an in vivo model have previously been only partially successful.

METHODS

The use of Matrigel has been reported to enhance tumorigenicity in a variety of solid tumors. This substance is derived from a mouse sarcoma and is a mixture of basement membrane proteins and growth factors. Meningioma cells obtained from human patients were placed in culture for 1 to 2 passages and then harvested and mixed with Matrigel and the mixture injected into the subcutaneous space in the flank of nude mice. Tumor volumes over time were measured at least three times a week and then harvested at 100 days postimplantation. Tumors were formalin-fixed, and histological examinations were performed. Immunohistochemistry was performed for human and mouse laminin, fibronectin, collagen Type IV, and epithelial membrane antigen.

RESULTS

Tumors developed in all 40 mice studied. Growth of meningioma tumors was dependent on total number of cells injected and independent of the total volume of tumor cells and Matrigel matrix. Histologically and immunohistochemically, the xenograft tumors were very similar to the original human tumors.

CONCLUSION

Matrigel is relatively easy to use and has a high rate of histologically confirmed meningioma tumor formation in an athymic mouse model. We plan to use this model for studying the growth of meningiomas in vivo.

Benjamin Winslow Dudley and early American trephination for posttraumatic epilepsy

Benjamin Winslow Dudley (1785-1870) was a Kentucky frontier surgeon who received basic medical education in the United States and extensive surgical training in Europe. He returned to Lexington to become a dominant figure and the most prominent surgical teacher in the Mississippi Valley. Written evidence of Dudley's operative accomplishments are sparse, but he seems to have combined the finest French (Dominique Jean Larrey, Guillaume Dupuytren) and British (Henry Cline, John Abernethy, Astley Cooper) surgical training with conservative and thoughtful patient selection. His operative endeavors in the preantiseptic era included trephination for posttraumatic epilepsy in six patients (1819-1832). This was the largest recorded series of such cases, and it stimulated other American surgeons to trephine for relief of posttraumatic seizures. Trephination for decompression and debridement was undertaken at the site of original injury to remove the cause of "cerebral excitement" and restore "corporeal and intellectual function." Dudley considered this a safe operation in "cautious, firm, and intelligent hands." He thought crowded urban hospitals were unsafe and attributed his better surgical results to the clean, rural Kentucky air. Dudley's achievement is contrasted with other Early American preantiseptic trephinations for posttraumatic epilepsy.

Risk factors of intracranial pressure monitoring in children with fiberoptic devices: a critical review

BACKGROUND

Intracranial pressure (ICP) monitoring has become standard in the management of severe head injuries. A variety of monitoring techniques and devices are available, each with advantages and disadvantages; however there have been few studies in the pediatric population.

METHODS

To study the risk factors, efficacy, and complication rate of fiberoptic ICP monitoring we studied 98 consecutive children with severe head injuries over a 2-year period. The average patient age was 9 years and most had an initial Childrens Coma Score (CCS) of 8 or less. The monitoring devices were placed in frontal parenchyma of all children and no prophylactic antibiotics were used. All fiberoptic catheter tips were cultured upon removal.

RESULTS

The average duration of ICP monitoring was 7 days; the usual range was 3-15 days, with the exception of one patient who underwent monitoring for 40 days. No complications occurred during insertion of the ICP monitors. Catheter tip cultures were positive for Staphylococcus epidermidis in 7% of the children, but none developed clinical features of CNS infection. The hospital location of placement or duration of ICP monitoring did not affect the rate of catheter tips with positive cultures. There was a 13% mechanical failure rate of the fiberoptic device.

CONCLUSIONS

We conclude that fiberoptic ICP monitoring is safe and effective; however, there is a relatively low mechanical failure rate. Infection in uncommon despite prolonged use and there is little risk of complications associated with placement of this monitor.

The prediction of power and efficiency during near-maximal rowing

The relationship between power and gross efficiency during near-maximal rowing, and physiological measures of strength, power, aerobic and anaerobic capacities and United State Rowing Association (USRA) performance tests (independent variables) was investigated among collegiate male rowers. Criterion measures of rowing power and gross efficiency were measured in a moving-water rowing tank, using an oar instrumented with strain gauges to assess force and a potentiometer to assess oar position. Bivariate correlation analysis (n = 28) indicated no relationship between the independent variables and rowing gross efficiency (P > 0.05). Rowing power [mean (SD) 483.4 (34.75) W] was significantly related to inboard leg extension strength (IL strength, r = 0.63), outboard leg extension strength (r = 0.45), combined leg extension strength (r = 0.45), and time to complete the USRA 2000-m simulated rowing race (r = -0.52; P <0.05). Stepwise regression using resampling cross-validation of 15 random samples (21 subjects per sample selected from a total group of 28 intercollegiate oarsmen) indicated that predictors of rowing power were IL strength and blood lactate following a peak oxygen uptake rowing test with significant multiple correlations of R 0.61 to 0.86 (P <0.05). The standard error of estimate (SEM) ranged from 18.1 to 29.9 W, or 5.3 (0.77) percent of the criterion value. Cross-validation with a hold-out group (seven subjects per sample) was performed for each equation and correlations ranged from R = 0.14 to 0.97 (SEM = 8.0 to 38.9 W). In conclusion, data from the present study suggest that to increase rowing power, training should emphasize leg strength and anaerobic training to decrease the level of lactate accumulated during rowing.

Introduction of the human Horsley-Clarke stereotactic frame

It is well known that the Horsley-Clarke frame was developed and first used by Robert Henry Clarke and the pioneer neurosurgeon Victor Horsley in 1906 for making lesions in the central nervous system of animals. The Horsley-Clarke frame was extensively used throughout the next 4 decades for excitation and lesion production in animals. Aubrey Mussen, a student of Clarke, designed a stereotactic apparatus for use in humans, but no procedures were actually performed with the instrument. It is less appreciated that a Horsley-Clarke frame was also constructed for human use and first applied for depth electroencephalography by Robert Hayne and Frederic Gibbs in 1947. The assumed relationship between external landmarks and intracranial structures provided initial target localization, and pneumoencephalography confirmed depth electrode position. In many ways, the work of Hayne and Gibbs paralleled the simultaneous efforts of Ernest A. Spiegel and Henry T. Wycis. Events leading to the development of stereotactic frames and their subsequent use in humans for the treatment of epilepsy, movement disorders, and psychosurgery are reviewed.

Effect of altitude on hand-held peak flowmeters

OBJECTIVE

To quantify the effect of altitude on the operational characteristics of hand-held peak flowmeters.

DESIGN

Altitude simulation within a hypobaric chamber combined with five constant simulated peak flows delivered from a computerized pump were used to test commercially available peak flowmeters.

SETTING

F.G. Hall Hyperbaric/Hypobaric facilities located at Duke University School of Medicine.

MEASUREMENTS

Two each of nine models of commercially available hand-held peak flowmeters and a volume spirometer were tested at six simulated altitudes (100, 500, 1,000, 1,500, 2,000, and 3,000 m) using five target peak flows. Each peak flow was injected into each meter twice. Forward stepwise regression was used to check for nonlinear relationships between altitude and peak expiratory flowmeter readings. Linear regression equations were fit to the data at each target flow across altitude. Effect of absolute peak flow was tested by analysis of covariance.

RESULTS

For these altitudes, linear relationships were found between altitude and measured peak flow. For all meters tested, the average decrease in peak flow ranged from -8.7% at the lowest target flow (123 L/min) to -6.5% at the highest target flow (702 L/min) for each 100 mm Hg decrease in barometric pressure (PB). Individual meters ranged from -12.3% at the lowest target flow to -4.4% at the highest target flow for 100 mm Hg decrease in PB. The spirometer had no significant changes associated with changes in PB. In all cases, the magnitude of the altitude effect, measured by percent change, decreased with increasing peak flow.

CONCLUSIONS

Peak expiratory flowmeters underread PEF as a function of both increasing altitude and increasing target peak flow.